I had this problem at first, if you get no Picture or sound when playin a video. Then it probably requires the latest codecs (drivers). I just downloaded these, and now i have no problems:
Try Div X (has Xvid codecs) if u get no picture or XVID if it still don't work.
If theres no sound try NIMO Codec.
These can be found on - http://www.xvid.com/
Starwars 2, Killin by numbers, K-pax, most films will work now.